The primary objective of this research is to investigate age-related changes in learning and memory in rats. Hormonally related agents such as OR-2766 (H-Met-Glu-His-Phe-d-Lys-Phe-OH) and desglycinamide vasopressin will be tested in senescent F-344 rats to determine if these drugs will attenuate the memory deficit for recently learned responses. Additionally, we plan to study age related changes in the central monamine systems and their relation to behavior. Finally, we plan a series of studies to examine the effects of hydergine, a mixture of 3 ergot alkaloids and piracetam, a drug that may be considered to be the result of the cyclization of gamma-amino-butyric acid (GABA). Both of these drugs have been reported to relieve symptoms in some senescent patients. BIBLIOGRAPHIC REFERENCES: McGaugh, J.L., and Gold, P.E. Modulation of memory by electrical stimulation of the brain. In: M.R. Rosenzweig and E.L. Bennett (Eds.), Neural Mechanisms of Learning and Memory. Cambridge, Mass: The MIT Press, 1976, pp. 549-560. McGaugh, J.L. Neurobiological aspects of memory. In: R.G. Grenell and S. Gabay (Eds.), Biological Foundations of Psychiatry. New York: Raven Press, 1976, pp. 499-525.